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International Journal of Environment Science and Technology
Center for Environment and Energy Research and Studies (CEERS)
ISSN: 1735-1472 EISSN: 1735-1472
Vol. 12, No. 11, 2015, pp. 3405-3416
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Bioline Code: st15319
Full paper language: English
Document type: Research Article
Document available free of charge
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International Journal of Environment Science and Technology, Vol. 12, No. 11, 2015, pp. 3405-3416
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Nitrous oxide emissions in a biofilm loaded with different mixtures of concentrated household wastewater
Todt, D. & Dörsch, P.
Abstract
Aerobic biofilm systems are increasingly used
for household wastewater treatment, but little is known
about their potential to emit nitrous oxide in response to
different loading conditions. We studied nitrification and
nitrous oxide production in a biofilm reactor that was
continuously fed with three different mixtures of household
wastewater. Higher proportions of blackwater increased
nitrification activity, which resulted in enhanced nitrite
accumulation and nitrous oxide emissions. Applying a
conceptual biofilm model together with the results of ancillary
batch incubations suggested that this was caused by
a higher proportion of slowly degradable compounds in
blackwater. Increasing amounts of blackwater would result
in less oxygen depletion by heterotrophic degradation in
outer biofilm layers, leading to nitrite accumulation by
enhanced ammonia oxidation as well as electron limitation
of denitrification in anoxic biofilm layers. Under such
conditions, nitrifier denitrification and incomplete
heterotrophic denitrification would be the prevailing sources
of nitrous oxide emission. These assumptions are
supported by an exponential increase in the determined
emission factor (nitrous oxide relative to oxidized ammonia),
which accounted for 0.7 with 20 % blackwater, 1.1
with 50 % blackwater, and 8.5 with 100 % blackwater in
the wastewater load.
Keywords
Biofilm; Nitrous oxide; Nitric oxide; Household wastewater; Blackwater; Greywater
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